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Partitioning of C into κ-carbides by Si addition and its effect on the initial deformation mechanism of Fe-Mn-Al-C lightweight steels

Title
Partitioning of C into κ-carbides by Si addition and its effect on the initial deformation mechanism of Fe-Mn-Al-C lightweight steels
Authors
Kim, C.W.Terner, M.Lee, J.H.Hong, H.U.Moon, J.Park, S.J.Jang, J.H.Lee, C.H.Lee, B.H.Lee, Y.J.
Issue Date
2019-02
Citation
Journal of Alloys and Compounds, 775, 554-564
Type
Article
Article Type
Article
Keywords
Atom probe tomography (APT)DislocationsFirst-principles calculationsMetals and alloysPrecipitation
ISSN
0925-8388
Abstract
The effect of Si addition on the initial deformation mechanism of Fe–30Mn–9Al–0.9C–0.5Mo cast lightweight steel has been investigated. Atomic-scale analysis by three-dimensional atom-probe tomography confirmed that Si addition accelerates the formation kinetics of the κ-carbide, and increases remarkably the partitioning coefficient of carbon by more than 2 times. Promotion of C partitioning into κ-carbides by Si addition leads to deformation localization in an aged state. This is attributed not only to the increase of the κ-carbide size associated with higher coherency strain, but also to higher frequency of Al-C bonding formation. First-principles calculations indicated that the energy required for a/2<110> shearing of κ-carbide in the aged 1%-Si steel is higher (561 mJ/m2) than that in the aged Si-free steel (494 mJ/m2). Therefore, Si addition leads to a significant energy difference for shearing and results in different shear bands formation. The operative deformation mechanism can be calculated for this alloy system as a function of precipitates volume fraction and size. It was determined that deformation proceeds primarily by κ-carbide shearing as long as the radius of κ-carbides is smaller than 13.4 nm. © 2018 Elsevier B.V.
URI
http://hdl.handle.net/20.500.11750/9408
DOI
10.1016/j.jallcom.2018.10.104
Publisher
Elsevier Ltd
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